Variable valve actuator assembly integrated with valve bridge

ABSTRACT

A integrated variable valve actuator assembly of a variable valve lift apparatus may include a rocker arm rotating on a rocker shaft and including an oil supply line with selectively provided oil, a fastener penetrating the side of the rocker arm and discharging oil supplied from the oil supply line through the oil passage, a valve bridge located at the bottom of the fastener and pressurizing valves, an actuator device including an actuator piston being inserted in the valve bridge and formed with an oil supply passage, and an actuator spring being inserted in the actuator piston and providing the actuator piston with elastic force, and a variable control device located at the bottom of the actuator piston and adjusting the heights of the actuator piston by a movement generated by the hydraulic pressure of oil supplied from the oil supply passage.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent Application Number 10-2010-0119803 filed in the Korean Intellectual Property Office on Nov. 29, 2010, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a integrated variable valve actuator assembly. More particularly, the present invention relates to a variable valve actuator assembly integrated with a valve bridge that comprises a variable control device and an actuator device at the lower end of the valve bridge and changes the height of the actuator device by selective supply of oil.

2. Description of Related Art

An internal combustion engine generates power by burning fuel in a combustion chamber in an air media that is drawn into the chamber. Intake valves are operated by a camshaft in order to intake in the air, and the air is drawn into the combustion chamber while the intake valves are open. In addition, exhaust valves are operated by the camshaft, and while the exhaust valves are opened, combusted mixed gas, which is exhaust gas, is discharged from the combustion chamber.

Optimal operation of the intake/exhaust valve depends on the load range of an engine. In other words, an appropriate lift or valve timing varies with the load range of an engine.

A variable valve lift (VVL) apparatus has been developed so as to embody an appropriate valve operation according to the rotation speed of an engine. For this, valves are operated with different lifts according to the load range of an engine.

However, the conventional variable valve lift apparatus has a problem in that the volume of the apparatus is quite large because of a device varying the valve lift irrelative to the valve bridge and a hydraulic pressure operating chamber is large when the valve lift is adjusted by the hydraulic pressure. In addition, it has a problem that the response speed of the system is much slower because the volume of the operating circuit for generating pressure is large.

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention have been made in an effort to address the problems mentioned above, and to provide an integrated variable valve actuator assembly integrated with a valve bridge. The integrated variable valve actuator assembly includes an actuator device and a variable control device integrated with the valve bridge so that the integrated variable valve actuator assembly can control the valve lift according to the load range of an engine and simultaneously improve responsiveness.

Various aspects of the present invention provide for a integrated variable valve actuator assembly integrated with a valve bridge, including a rocker arm rotating on a rocker shaft and having an oil supply line for selectively supplying oil therein, a fastener penetrating the side portion of the rocker arm and discharging the oil supplied from the oil supply line through an oil passage formed therein, a valve bridge that is located at the lower end of the fastener and applies pressure on valves, an actuator device having an actuator piston that is inserted in the valve bridge and is formed with an oil supply passage for discharging the oil passing through the oil passage and an actuator spring that is inserted in the actuator piston and exerts elastic force on the actuator piston, and a variable control device that is located at the lower end of the actuator piston and can move by the pressure of the oil supplied through the oil supply passage so as to change the height of the actuator piston.

Various aspects of a snap ring according to the present invention are characterized in that it is located on the exterior circumference of the actuator piston.

The variable control device according to various aspects of the present invention may include a variable control piston that is formed at the lower end of the actuator piston so as to selectively block upward or downward movements of the actuator piston, and is inserted in an insertion hole of a variable control device formed at the lower portion of the valve bridge, a variable control spring that contacts the variable control piston and exerts elastic force on the variable control piston, and a plate that supports the variable control spring. An aspect of the variable control device is characterized in that a plurality of variable control devices is provided.

The variable control piston according to various aspects of the present invention may include a body blocking upward or downward movements of the actuator piston and an edge restricting movements of the actuator piston. An aspect of the actuator piston is characterized in that the displacement of the actuator piston is equal to the diameter of the body in the variable control piston.

As explained above, using the variable control device and through the selective supply of oil the actuator device can adjust the valve lift to multiple positions. Both the structures and the operation procedures are simple since the actuator device and the variable control device are integrated with the valve bridge, and the volume of the chamber operated by the hydraulic pressure is small. Variable control performance is improved by increasing the response speed of the system because the volume of the operating circuit in which the pressure is generated is small.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary variable valve lift apparatus according to the present invention.

FIG. 2 is a cross-sectional view of an exemplary variable valve lift apparatus including a integrated variable valve actuator assembly according to the present invention.

FIG. 3 is an exploded perspective view of an exemplary actuator device, a variable control device, and a valve bridge according to the present invention

FIG. 4A shows an unexploded perspective view of FIG. 3

FIG. 4B shows a partial cross-sectional view of FIG. 4A along line B-B

FIG. 4C shows a partial cross-sectional view of FIG. 4A along line C-C

FIG. 5 is a cross-sectional view of an exemplary valve lift apparatus that operates in a high lift mode according to the present invention

FIG. 6 is a cross-sectional view of an exemplary inner valve bridge in a high lift mode according to the present invention

FIG. 7 is a cross-sectional view of an exemplary valve lift apparatus that operates in a low lift mode according to the present invention

FIG. 8 is a cross-sectional view of an exemplary inner valve bridge in a low lift mode according to the present invention.

FIG. 9 is a graph that shows the variation of valve lifts according to various aspects of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

FIGS. 1-2 show a variable valve lift apparatus 100 including a integrated variable valve actuator assembly according to various embodiments of the present invention. FIG. 3 is an exploded perspective view of an actuator device 350, a variable control device 400, and a valve bridge 310 according to various embodiments of the present invention.

Referring to FIGS. 1-4, a integrated variable valve actuator assembly according to various embodiments of the present invention includes a variable valve actuator that opens/closes valves by a rocker arm 500 rotating on a rocker shaft 570 and having an oil supply line 505 that is selectively supplied with oil therein, a fastener such as a screw 520 penetrating the side portion of the rocker arm 500 and discharging oil 51 supplied from the oil supply line 505 through an oil passage 525 formed therein, a socket 550 being connected with the lower end of the screw 520, and the valve bridge 310 located at the lower end of the screw 520 with a protrusion 315 formed at the lower end thereof and applying pressure on valves 200.

Referring also to FIGS. 1-4, the integrated variable valve actuator assembly includes the actuator device 350 and the variable control device 400. The actuator device 350 adjusts the valve lift while being inserted in the valve bridge 310 and moving upward and downward. Valve insertion grooves 380 a and 380 b are formed at the lower side of the valve bridge 310 and a valve piston 240 can be inserted into the valve bridge 310. The variable control device 400 controls the movements of the actuator device 350.

Referring to FIG. 2, the fastener such as a screw 520 is fixed by a nut 510. Oil supplied from the oil supply line 505 can move through the oil passage 525 formed therein, and a ball 515 is located approximately in the middle of the fastener 520 along its length direction to prevent the supplied oil from leaking out.

Referring to FIGS. 2-3, the actuator device 350 includes an actuator piston 320, an actuator spring 330, and a snap ring 340. The actuator piston 320 is inserted into the valve bridge 310, optionally and preferably the center of the valve bridge 310, and contacts the socket 550. An oil supply passage 325 is formed so that the oil having passed through the oil passage 525 formed in the screw 520 can be discharged. A portion of the actuator piston 320 is formed as a step where the snap ring 340 can be placed. The actuator spring 330, being inserted in the actuator piston 320, exerts elastic force on the actuator piston 320.

Referring to FIGS. 4B and 4C, the protrusion 315 formed at the lower portion of the valve bridge 311 prohibits the actuator spring 330 from bending from side to side, and simultaneously supports the actuator piston 320 firmly.

Referring to FIGS. 3-4, the variable control device 400 includes a variable control piston 420, a variable control spring 440, and a plate 460. The variable control piston 420 is inserted into the insertion holes of variable control devices 390 a, 390 b, and 390 c that are formed at the lower portion of the valve bridge 311, and can selectively vary the height of the actuator piston 320 by moving back and forth at the lower end of the actuator piston 320. The plate 460, being located at the outmost part of the insertion holes of the variable control devices 390 a, 390 b, and 390 c, performs functions such as supporting the variable control spring 440. The variable control spring 440 contacts the variable control piston 420 so that it pushes the variable control piston 420 forward.

Referring further to FIGS. 3-4, the variable control piston 420 includes a body 422 performing functions of prohibiting the actuator piston 320 from descending directly, and an edge 421 protruding from the body 422 and playing a role of preventing the variable control piston 420 from advancing further. When oil is not supplied, the height of the actuator piston 320 is low because the variable control piston 420 protrudes to its highest point by the variable control spring 440. But when oil is supplied, the descending length of the actuator piston 320 becomes longer because the variable control piston 420 moves backward by the hydraulic pressure generated by the supplied oil.

The features presented in the above mentioned figures show three of variable control devices 400 evenly placed along the actuator piston 320 as the center thereof. But the number of variable control devices 400 is not restricted to three, and multiple variable control devices 400 can be provided. A person having ordinary skill in the art that pertains to the present invention can modify the number of variable control devices 400 to be single or plural as necessary in the range of the normal creativeness of the person.

In addition, referring to FIG. 6 and FIG. 8, the height D2 of the upward and downward movements of the actuator piston 320 can be equal to the diameter D1 of the body 422, and they can have the same value as the valve lift D, which is defined as the difference of the valve lifts between two modes—the variable control on (the low lift mode) and the variable control off (the high lift mode).

Hereinafter, the operation of the integrated variable valve actuator assembly according to one of various exemplary embodiments of the present invention is described referring to the accompanying drawings.

Shown in FIG. 1 is the perspective view of a variable valve lift apparatus 100. As the rocker arm 500 that is connected with a rocker shaft 570 rotates, the fastener such as a screw 520 and the socket 550 located at the end of the rocker arm 500 move upward and downward. When the socket 550 applies pressure to the valve bridge 310, the valve bridge 310 applies pressure to valves 200. Firstly, the valve bridge 310 applies pressure on the valve piston 240, and the valve piston 240 moves upward and downward with a valve stem 210 and a valve surface 220 recovering the elastic force of a valve spring 230. This is achieved by the rotation of a cam 600. As the cam 600 rotates, the lobe of the cam 600 contacts the rocker arm roller 560 and the rocker arm 560 rotates on the rocker shaft 570. This procedure is fulfilled by selectively supplying oil using a solenoid valve 650.

Hereinafter, operating procedures according to one of various exemplary embodiments of the present invention are described for a high lift mode and a low lift mode respectively with the accompanying drawings.

During the high lift mode, supply of oil is stopped. As shown in FIGS. 5-6, the variable control spring 440 pushes the variable control piston 420 to the bottom of the valve bridge 310 since there is no oil supplied. As the variable control piston 420 advances towards the actuator piston 320 by the elastic force of the variable control spring 440, the actuator piston 320 cannot descend further by the variable control piston 420 when the rocker arm 500 rotates on the rocker shaft 570. Therefore, the valve lift is achieved as much as the fastener 520 and the socket 550 descend. In this way, the high lift mode is fulfilled.

On the other hand, oil 51 is supplied by a solenoid valve 650 in the low lift mode. As shown in FIGS. 7-8, the oil 51 passes through the oil supply line 505 and the oil passage 525 and then through the oil supply passage 325 formed in the actuator piston 320. At this time, the variable control piston 420 moves backward by recovering the elastic force of the variable control spring 440 and by the hydraulic pressure of the supplied oil 51. Therefore, as the rocker arm 500 rotates, the actuator piston 320 descends as much as the diameter D1 of the body 422 of the variable control piston 420, but does not apply pressure on the valves 200. In other words, lost motion is fulfilled. As a result, the actuator piston 320 descends the length D2 as shown in FIG. 8, contracting to the displacement during the high lift mode. The displacement of the actuator piston 320 is equal to the diameter D1 of the body 422 in the variable control piston 420. Therefore, D1 and D2 are equal to the difference of the valve lifts D, as shown in FIG. 9.

As described above, the valve lift can be changed among multiple positions by selectively varying the valve lift supplying oil. The actuator device 350 and the variable control device 400 are integrated with the valve bridge 310. As such, the structures and the operation procedures of the apparatuses are simple, and the volume of the operating circuit in which a pressure can be generated is smaller than the conventional variable valve life apparatuses. Moreover, the response speed of the systems is improved.

For convenience in explanation and accurate definition in the appended claims, the terms “upper” or “lower”, “front” or “rear”, “inside” or “outside”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. An integrated variable valve actuator assembly comprising: a rocker arm rotating on a rocker shaft and including an oil supply line formed therein for selectively supplying oil; a fastener penetrating a side portion of the rocker arm and including an oil passage formed therein for discharging oil supplied from the oil supply line; a valve bridge that is located at a lower end of the fastener and applies pressure on valves; an actuator device including an actuator piston that is inserted in the valve bridge and is formed with an oil supply passage for discharging oil passing through the oil passage, and an actuator spring that is inserted in the actuator piston and exerts elastic force on the actuator piston; and a variable control device that is located at the lower end of the actuator piston and can move by the pressure of oil supplied through the oil supply passage so as to change the position of the actuator piston.
 2. The integrated variable valve actuator of claim 1, wherein a snap ring is located on the exterior circumference of the actuator piston.
 3. The integrated variable valve actuator assembly of claim 1, wherein the valve bridge is formed with protrusions at the lower portion of the valve bridge preventing the actuator spring from bending from side to side, and supporting the actuator piston.
 4. The integrated variable valve actuator assembly of claim 1, wherein the variable control device comprises: a variable control piston that is inserted in an insertion hole of the variable control device formed at the lower portion of the valve bridge and contacts the lower end of the actuator piston; a variable control spring that contacts the variable control piston and exerts elastic force on the variable control piston; and a plate that supports the variable control spring.
 5. The integrated variable valve actuator assembly of claim 4, wherein a plurality of said variable control devices are provided.
 6. The integrated variable valve actuator assembly of claim 4, wherein the variable control piston comprises a body blocking upward or downward movements of the actuator piston and an edge restricting movements of the actuator piston.
 7. The integrated variable valve actuator assembly of claim 1, wherein the actuator piston can be positioned at multiple modes.
 8. The integrated variable valve actuator assembly of claim 7, wherein the actuator piston can be positioned at a low lift mode or at a high lift mode.
 9. The integrated variable valve actuator assembly of claim 7, wherein the displacement of the actuator piston is equal to the diameter of the body in the variable control piston. 